Purpose: We compared the results of a preoperative (111)In-capromab pendetide scan co-registered with computerized tomography with pathological findings in the surgically excised prostate to determine whether the scan can efficiently detect cancer in the prostate.
Materials and methods: This prospective trial included 25 hormone naïve men with clinically localized prostate cancer who underwent (111)In-capromab pendetide single photon emission computerized tomography/computerized tomography as part of the preoperative evaluation. In addition to routine histological analysis, representative prostate sections were stained for prostate specific membrane antigen using the same antibody used in the scan. A pathologist and a radiologist were blinded to pathology and imaging findings, respectively. Prostate specific membrane antigen immunohistochemistry was correlated with the 3-dimensional location of the prostate specific membrane antigen signal detected by scan.
Results: Scan sensitivity was 37% to 87% for 4 quadrants (right vs left and apical vs basal) with 0% to 50% specificity, as validated by final pathological assessment of the same quadrants. Stratifying positive scan signal strength did not statistically improve specificity (p = 0.35). There was no significant correlation between prostate specific membrane antigen over expression and tumor stage distribution (p = 0.23).
Conclusions: The scan did not localize prostate cancer to a particular quadrant based on comparison with radical prostatectomy specimen pathology. The antibody used has affinity for benign and malignant prostatic glands in excised, formalin fixed prostate tissue, which may contribute to low scan specificity in vivo. The scan cannot be used to reliably detect or image cancer foci in the prostate.